2. Set amount

Amount:

3. Post fingerprint to the Steem chain via

Tamperproof blockchain-based file fingerprint integrity

Proof.ink's service is pretty straightforward. If you have a document of which you want to know with 100% certainty that it's contents has not been changed, tampered with or altered in any form, use Proof.ink.

Proof.ink works by fingerprinting your file (no matter how big), without the need to upload it, inside your browser. The result of this calculation is a unique SHA256 hash / fingerprint of your file.

By enabling you to store the fingerprint publicly on the Steem blockchain, Proof.ink can guarantee the integrity of the fingerprint of the file as how it was created at a given time by a given user. This way others can use this service to validate the fingerprint on the blockchain and against the file they receive.

The Steem chain serves as a public accessible ledger with provable immutability at it's core, for a trustless public store of the derived file's fingerprint.

Validate your file

So you have received a file along with a proof.ink.*.txt certificate file and want to validate the integrity of the original file?

Step 1: Select files to be validated. Select both the original file and the proof.ink.*.txt certificate file in one go.

select original file + proof.ink.txt

Questions & Answers

What do you do with my files?

Actually.... Nothing! This site (or app if you will) solely run in your browser. The fingerprinting happens without the need for you to upload your data. Try it! You can disconnect from the internet if you want. After the fingerprinting you can store the resulting 'hash' or fingerprint on the Steem blockchain.

What do you need from me?

Well... You need a file to be fingerprinted. And then you need a Steem account. Don't have one? Sign up instantly now!

What is a hash/checksum/fingerprint?

From Wikipedia: A checksum is a small-sized datum derived from a block of digital data. Checksums are often used to verify data integrity but are not relied upon to verify data authenticity.

Why is hashing useful for proving file integrity?

The hashing function used on this site is meant for one-way, so infeasible to invert.

The fingerprint is deterministic so the same data always results in the same fingerprint. This fact is used to help you prove the immutability of a given file you want to analyse using Proof.ink

Depending on the filesize, it is quick to compute the hash

It is infeasible to generate a message from its hash value except by trying all possible messages

A small change to a document should change the fingerprint so extensively that the new fingerprint appears uncorrelated with the old fingerprint

It is infeasible to find two different messages with the same fingerprint

What is the Steem Blockchain?

The Steem blockchain is a decentralised proof of stake blockchain with 3 second blocktimes and quick confirmations. By using the Steem blockchain Proof.ink can build a trustless store of fingerprints on a blockchain which responds near instant and therefore keep the service "snappy". A fingerprint is ready while you wait, depending on your processor speed and filesize, and storing them doesn't take longer than 3 seconds if you have a Steem account readily available.

Storing the fingerprint on the Steem chain is done by sending a public transfer to the @proof.ink account on the Steem chain, including your 'fingerprint' in the message's "memo"-field. Intrinsic to transferring is that you need to send a bit of Steem or Steem dollars along. It is up to you to decide how much Steem you send. Any funds you send will be used to maintain the service. A recommended amount is pre-filled, but you can go as low as 0.001 Steem/SBD or as high as sending all the Steem/SBD you have!